A LABORATORY SCALE AIRLIFT HELICAL PHOTOBIOREACTOR TO INCREASE BIOMASS OUTPUT RATE OF PHOTOSYNTHETIC ALGAL CULTURES

The helical air‐lift reactor of 0·315 1 capacity provides an improved way to cultivate photosynthetic organisms when compared to a 0·625 1 stirred reactor. The improvement results from an approximately three‐fold increase in the surface area: volume ratio of the reactor. Continuous operation of the helical reactor at a dilution rate of 0·025 h−1 permitted a light‐limited photosynthetic culture of Porphyridium cruentum to be maintained at a steady state biomass concentration of 4·6 g l−1 compared to 1·7 g l−1 in the stirred reactor under similar illumination. When operated at an air flow rate of 0·75 1 min−1, the volumetric oxygen transfer coefficient was 160 h−1 in the helical reactor and a Reynolds number of 2000 was obtained. Copyright © 1990, Wiley Blackwell. All rights reserved